JP2007106295A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in noise performance from the time when it is new through the time after travelling a long distance by restricting occurrence of eccentric abrasion in a tire fixed in rotating direction thereof and having a pattern of block motif. <P>SOLUTION: This pneumatic tire is formed with multiple blocks 4a, 4b and 4c on a tread surface 1 by dividing with a plurality of circumferential grooves 2 extended in the tire circumferential direction and multiple lateral grooves 3a, 3b, 3c and 3d obliquely crossing the circumferential grooves and arranged with a plurality of different pitches P1, P2 and P3 in the tire circumferential direction. Inclination angle α of a tire anti-rotating directional side wall surface of the block facing the lateral grooves 3a, 3b and 3c is set larger than inclination angle β of a tire rotating directional side wall surface thereof, and inclination angle inside the unit arrangement of each of the pitches is set to be larger as the pitch gets larger. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire. More specifically, the present invention relates to a noise from a new article to a long-distance run by suppressing the occurrence of uneven wear in a tire having a block-based pattern with a specified rotational direction. The present invention relates to a pneumatic tire with improved performance.

  Conventionally, in tires with a block-tone pattern on the tread surface and a specified rotation direction, slippage on the road surface on the counter-rotation direction side (kicking side) of the block surface is greater than on the rotation direction side (stepping side). It is known that uneven wear called heel and toe wear tends to occur early. In addition, when such uneven wear occurs, the ground pressure of the block changes, which makes it easier to generate noise in the vehicle interior, and this vehicle interior noise has a greater effect on blocks with a larger pitch than blocks with a smaller pitch. It is known to affect.

  As a measure to suppress uneven wear that occurs in the block, the inclination angle formed by the stepping side of the block and the wall surface on the kicking side with respect to the normal direction of the tread surface is made larger on the kicking side than on the stepping side. It is known that this can be solved by increasing the rigidity on the kicking side (see, for example, Patent Document 1).

However, in general, the block arrangement in the block pattern is arranged with multiple pitches of different sizes in the tire circumferential direction in order to reduce the pattern noise generated when the block hits the road surface by white noise. Like to do. Since the blocks are pitch-variated in this way, even if the wall surface of the block is made different between the stepping side and the kicking side as described above, the degree of wear differs for each block having a different pitch. Therefore, the occurrence of uneven wear could not be completely eliminated. Moreover, since uneven wear occurs unevenly for each block, it cannot be said that the vehicle interior noise can be completely eliminated.
JP 2004-182075 A

  The present invention solves the above-described conventional problems, and suppresses the occurrence of uneven wear in a tire having a block-based pattern in which the direction of rotation is specified, thereby extending from a new article to after a long distance run. The object is to provide a pneumatic tire with improved noise performance.

  The pneumatic tire of the present invention has a plurality of circumferential grooves extending in the tire circumferential direction on the tread surface, and a plurality of lateral grooves arranged at a plurality of different pitches in the tire circumferential direction while obliquely intersecting the circumferential grooves. In a pneumatic tire in which a large number of blocks are defined by the direction groove and the rotation direction is specified, the inclination angle α of the tire anti-rotation direction side wall surface of the block facing the lateral groove is defined as the tire rotation direction side wall surface. And a larger pitch according to the size of the pitch, the tilt angles α and β in the unit array from the maximum pitch to the minimum pitch of the pitch.

  According to the present invention, in a tire having a block-based pattern and designated in the rotational direction, the inclination angle α of the groove wall surface on the tire anti-rotation direction side (kick-out side) of the block facing the lateral groove is set in the tire rotation direction. Since the slope angle β and β in the unit array from the maximum pitch to the minimum pitch are made larger as the pitch is larger than the slope angle β of the groove wall on the side (stepping side). By suppressing uneven wear that occurs differently for different blocks, and making the wear of the blocks around the entire tire uniform, it is possible to improve the noise performance from the time of a new product to after long distance running it can.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a partial plan view showing an example of a tread surface of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line XX of FIG.

  In FIG. 1, a tread surface 1 includes a plurality of (four in the figure) circumferential grooves 2 extending in the tire circumferential direction, and a plurality of different pitches (in the tire circumferential direction) while obliquely intersecting the circumferential grooves 2. In the figure, a large number of blocks 4a, 4b, 4c are defined by a large number of lateral grooves 3a, 3b, 3c, 3d arranged at P1, P2, P3), and the rotation direction R of the tire is designated. . The pitch lengths of the plurality of different pitches P1, P2, and P3 are smaller in the order of P1, P2, and P3. Therefore, in the following description, the pitch P1 is referred to as a large pitch, the pitch P2 is referred to as a medium pitch, and the pitch P3 is referred to as a small pitch.

  The inclination angle formed with respect to the normal direction of the tread surface on the wall surfaces of the blocks 4a, 4b, and 4c facing the lateral grooves 3a, 3b, and 3c is, as shown in FIG. The wall inclination angle α (αa, αb, αc in the figure) is larger than the inclination angle β (βa, βb, βc in the figure) of the tire rotation direction side (stepping side) wall (αa> βa, αb). > Βb, αc> βc), and the inclination angles αa, αb, αc and βa, βb, βc in the unit array from the large pitch P1 to the small pitch P3 are increased as the pitch increases. Yes. That is, the relationship between the inclination angles αa, αb, and αc is αa> αb> αc, and the relationship between the inclination angles βa, βb, and βc is βa> βb> βc.

  As a result, uneven wear that occurs differently for each of the blocks 4a, 4b, and 4c having different pitches P1, P2, and P3 is efficiently suppressed, and the wear of the blocks on the entire circumference of the tire is made uniform throughout. The noise performance from when it is new to after long distance running can be improved.

  In the present invention, the cross-sectional area in the cross section orthogonal to the longitudinal direction of the lateral grooves 3a, 3b, and 3c in each of the pitches P1, P2, and P3 may be increased as the pitch decreases. That is, the cross-sectional areas of the lateral grooves 3a, 3b, and 3c may be adjusted to be the maximum at the small pitch P3 and the minimum at the large pitch P1. That is, by adjusting the extrusion amount of rubber by the molding bone of the mold, the cross-sectional areas of the lateral grooves 3a, 3b, and 3c in the pitches P1, P2, and P3 are changed to change the large pitch P1 to the small pitch P3. The radial rigidity between the blocks 4a, 4b, and 4c up to is equalized to suppress the occurrence of uneven wear.

  Further, in the lateral grooves 3a, 3b, 3c in the unit array from the large pitch P1 to the small pitch P3, the increasing rate of the cross-sectional area of the lateral groove 3c with the small pitch P3 with respect to the lateral groove 3a with the large pitch P1. May be adjusted to 0.15 to 1.5%. As a result, the radial rigidity of the blocks 4a, 4b, and 4c at the respective pitches P1, P2, and P3 can be made substantially uniform, so that uneven wear that occurs in the blocks 4a, 4b, and 4c can be more efficiently suppressed. it can.

  The cross-sectional areas of the lateral grooves 3a, 3b, and 3c described above are the cross-sectional areas of the lateral grooves 3a, 3b, and 3c in a cross section orthogonal to the longitudinal direction of the lateral grooves 3a, 3b, and 3c, as shown in FIG. The area surrounded by the groove wall and the virtual extension line Q of the tread surface 1 is said.

In the present invention, when the groove depth of the lateral grooves 3a, 3b, and 3c is D and the groove width is W, the inclination angles αa, αb, and αc are set to 0.90 × tan ⁻¹ (2D / W) or less. The inclination angles βa, βb, and βc are set to (0.10 to 0.75) × tan ⁻¹ (2D / W), preferably (0.3 to 0.5) × tan ⁻¹ (2D / W). It may be set (see FIG. 3). When the inclination angles αa, αb, and αc exceed 0.9 × tan ⁻¹ (2D / W), the rigidity of the edge portion on the kick-out side of the blocks 4a, 4b, and 4c becomes too high, and uneven wear tends to occur. At the same time, the arc at the bottom of the groove is narrowed, and cracks are likely to occur. In addition, when the inclination angles βa, βb, and βc are less than 0.10 × tan ⁻¹ (2D / W), uneven wear tends to occur, and when it exceeds 0.75 × tan ⁻¹ (2D / W), the groove bottom The arc portion is narrowed and cracks are likely to occur.

  Furthermore, the inclination angles αa, αb, and αc may be adjusted to be 1.6 to 2.0 times the inclination angles βa, βb, and βc, respectively. That is, by making 1.6βa ≦ αa ≦ 2.0βa, 1.6βb ≦ αb ≦ 2.0βb, 1.6βc ≦ αc ≦ 2.0βc, uneven wear on the surfaces of the blocks 4a, 4b, 4c Can be more efficiently suppressed.

  In the above-described embodiment, the case where the large pitch P1, the medium pitch P2, and the small pitch P3 among the plurality of pitches P1, P2, and P3 on the tread surface 1 are arranged adjacent to each other has been described. The entering tires usually have tread patterns formed by randomly arranging 2 to 7 types of pitches in the tire circumferential direction. Further, the planar form of the grooves constituting the tread pattern is not limited to that shown in FIG. 1 and can be formed by combining many planar forms.

  Conventional tire (conventional example) in which the tire wall size (195 / 65R15) and the tread pattern (FIG. 1) are shared, and the inclination angle of the block wall surface and the cross-sectional area of the lateral groove in FIG. Tires of the present invention (Examples 1 and 2) were produced. In addition, the tread pattern of each tire was a repeated arrangement of a large pitch P1, a medium pitch P2, and a small pitch P3.

  The above three types of tires were evaluated for noise performance when they were new and after long-distance running by the following method, and the results are also shown in Table 1 using an index with the conventional tire as 100. The larger the value, the better.

[Noise performance when new]
Each tire is filled with air pressure 230 kPa, mounted on the front and rear wheels of an FF vehicle (displacement 1800 cc, sedan), and the noise in the passenger compartment when running a test course consisting of rough asphalt road surface at 100 km / h, Measurements were taken with a sound collection microphone installed in the center of the driver's backrest.

[Noise performance after long distance travel]
Each tire is filled with air pressure 230 kPa, mounted on the front and rear wheels of an FF vehicle (displacement 1800 cc, sedan), traveled 10,000 km on a general road, and then traveled on a test course consisting of asphalt road at 100 km / h In the same manner as described above, the noise in the passenger compartment was measured with a sound collecting microphone installed in the center of the driver's seat back.

  From Table 1, it can be seen that in the tire of the present invention, noise in the passenger compartment is suppressed from when it is new to after long distance running, compared to the conventional tire.

It is a partial top view which shows an example of the tread surface of the pneumatic tire by embodiment of this invention. It is XX arrow sectional drawing of FIG. It is explanatory drawing which expands and shows the cross section of the horizontal direction groove | channel of the tire of FIG.

Explanation of symbols

1 Tread surface 2 Circumferential groove 3a, 3b, 3c, 3d Lateral groove 4a, 4b, 4c Block P1 Large pitch P2 Medium pitch P3 Small pitch R Tire rotation direction

Claims (5)

A large number of blocks are formed on the tread surface by a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of lateral grooves obliquely intersecting the circumferential grooves and arranged at a plurality of different pitches in the tire circumferential direction. In a pneumatic tire that is partitioned and whose rotation direction is specified,
The inclination angle α of the tire anti-rotation side wall surface of the block facing the lateral groove is made larger than the inclination angle β of the tire rotation direction side wall surface, and in the unit array from the maximum pitch to the minimum pitch of the pitch A pneumatic tire in which the inclination angles α and β are increased with increasing pitch according to the size of the pitch.   2. The pneumatic tire according to claim 1, wherein a cross-sectional area in a cross section orthogonal to a longitudinal direction of the lateral groove is increased as a pitch becomes smaller according to the size of the pitch.   In the lateral grooves in the unit array from the maximum pitch to the minimum pitch, the increase rate of the cross-sectional area of the lateral groove with the minimum pitch is 0.15 to 1.5 with respect to the cross-sectional area of the lateral groove with the maximum pitch. The pneumatic tire according to claim 2, wherein the pneumatic tire is%. When the groove depth of the lateral groove is D and the groove width is W, the inclination angle α is set to 0.90 × tan ⁻¹ (2D / W) or less, and the inclination angle β is set to (0.10 to 0). .75) × tan ⁻¹ (2D / W). The pneumatic tire according to claim 1, 2, or 3. The pneumatic tire according to claim 1, wherein the inclination angle α is 1.6 to 2.0 times the inclination angle β.

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